A3 Sportback 8PA CJ4 Space Saver Spare Wheels

My A3 8PA has a 125/70 R16 space saver spare wheel.

The four road wheels are 255/45 R17 alloys.

I've recently retrofitted a westfalia detachable towbar system.

After much searching & looking on a 'popular auction site' I've discovered that only the spare wheel foam tool insert for the 18" space saver spare has the cut-out for the removable section of the towbar - the 16" version doesn't have enough space.


Sooo, my question is ... If I purchased an 125/70 R18 space saver spare wheel I could then purchase the foam insert & be able to store the towball inside the car - great. But would the 18" space saver be legal? Would it be an MOT failure? Would it safe to run with 3 main tyres being 17" & the spare being 18" ?

(I've checked, by borrowing from a colleague at work, the 18" will fit in the well & his foam insert is the one that I'm looking for).

Thanks

Adrian

Unfortunately, I don't think that will work. The spare wheel fits 'upside down' in the well in the boot, the foam insert fits inside of the upturned wheel. The foam insert that I need will fit inside of an 18" space saver wheel but is too big to fit inside of the 16" space saver that came with the car, hence my wanting to change out the R16 space saver for an R18.